My personal opinion is that all the Tim Holtz merchandise is over-priced. However, some items are pretty useful and can be purchased when they're on sale.
This stamp collection has lots of variety, which makes it pretty useful. However, some of the stamps are so detailed that they may show up as indistinct blobs on some types of paper. Be sure to test the stamps on scraps first to learn how much ink to use and what types of paper will work best.